An early Saturday explosion at Harvard Medical School’s Goldenson building was intentional but caused no injuries, authorities said. Responding to a fire alarm, a campus officer encountered two unidentified people who fled before the officer reached the scene of the blast. The Boston Fire Department later determined the explosion was intentional, and a sweep found no additional devices. Police released grainy images showing two people in face coverings and what appeared to be sweatshirts.

Prepared by Emily Rhodes and reviewed by editorial team.